Pfefferbaum A, Desmond J E, Galloway C, Menon V, Glover G H, Sullivan E V
Neuroscience Program, SRI International, Menlo Park, California 94025, USA.
Neuroimage. 2001 Jul;14(1 Pt 1):7-20. doi: 10.1006/nimg.2001.0785.
Chronic alcoholism is associated with impairment in sustained attention and visual working memory. Thus, alcoholics have reduced ability, but not necessarily inability, to perform these executive tasks, assumed to be subserved by regions of prefrontal cortex. To identify neural substrates associated with this impairment, we used functional MRI (fMRI) to determine whether alcoholics invoke the same or different brain systems as controls when engaged in working memory tasks that the two groups were able to perform at equivalent levels. The fMRI spatial working memory paradigm instructed subjects to respond with a button press when a target position was either in the center of the field (match to center) or matched the spatial position of one presented two items previously (match 2-back) or to rest. Using whole-brain fMRI, alcoholics showed diminished activation frontal cortical systems compared to controls (bilateral dorsolateral prefrontal cortex) when responding 2-back vs rest. In the center vs rest contrast, the control group compared with the alcoholic group activated a large expanse of prefrontal cortex (including Brodmann areas 9, 10, and 45), whereas there was significantly greater activation by the alcoholic group relative to the control group localized more posteriorly and inferiorly in the frontal cortex (area 47). Examination of within group activation patterns revealed two different patterns of activation: the control group exhibited activation of the dorsal ("Where?") stream for visual spatial working memory processing, whereas the alcoholic group exhibited activation of the ventral ("What?") stream and declarative memory systems to accomplish the spatial working memory task. The differences in the pattern of brain activations exhibited by the alcoholic and control groups, despite equivalence in behavioral performance, is consistent with a functional reorganization of the brain systems invoked by alcoholic individuals or invocation of an inappropriate brain system when engaged in a visual spatial task requiring working memory.
慢性酒精中毒与持续注意力和视觉工作记忆受损有关。因此，酗酒者执行这些执行任务的能力下降，但不一定丧失能力，这些任务被认为由前额叶皮质区域负责。为了确定与这种损伤相关的神经基质，我们使用功能磁共振成像（fMRI）来确定酗酒者在进行两组能够以同等水平执行的工作记忆任务时，是否调用与对照组相同或不同的脑系统。fMRI空间工作记忆范式指示受试者在目标位置位于视野中心（匹配中心）或与之前呈现的两个项目之一的空间位置匹配（匹配2-back）时按下按钮做出反应，或者休息。使用全脑fMRI，与对照组相比，酗酒者在进行2-back与休息对比时，额叶皮质系统的激活减少（双侧背外侧前额叶皮质）。在中心与休息对比中，对照组与酗酒组相比激活了大片前额叶皮质（包括布罗德曼区域9、10和45），而酗酒组相对于对照组在额叶皮质更靠后和靠下的区域（区域47）有明显更大的激活。对组内激活模式的检查揭示了两种不同的激活模式：对照组在视觉空间工作记忆处理中表现出背侧（“哪里？”）流的激活，而酗酒组表现出腹侧（“什么？”）流和陈述性记忆系统的激活以完成空间工作记忆任务。尽管行为表现相当，但酗酒组和对照组所表现出的脑激活模式差异，与酗酒个体调用的脑系统功能重组或在进行需要工作记忆的视觉空间任务时调用不适当的脑系统是一致的。
